Quantum Quench Research Paper

TERM PAPER - 2

QUANTUM QUENCH AND ENTANGLEMENT THERMODYNAMICS OF BTZ BLACK HOLE

QUANTUM QUENCH -

A quantum quench is a protocol in which you prepare a closed quantum system in an eigenstate of one Hamiltonian H^0H^0 and then have the system evolve dynamically in time under a different Hamiltonian H^0+H^1H^0+H^1. This is sometimes referred to as a "sudden" quench, to contrast with "slow" quench protocols where the Hamiltonian is continuously changed from H^0H^0 to H^0+H^1H^0+H^1 over some finite time span. When there is no qualification, my experience is that the term quantum quench usually refers to a sudden quench.

It's worth noting that a quench, as defined above, is a pretty generic scenario. If you've taken a quantum mechanics

This state is typically not the ground state of the perturbed Hamiltonian, but unless your perturbation takes you near or across a quantum phase transition, the state is still close to the new Hamiltonian's ground state. Put another way, it's the ground state of the perturbed Hamiltonian plus some low-energy excitations. Since a lot of condensed matter physics is about understanding the behavior of low-energy excitations over ground states, quantum quenches are a natural scenario for studying dynamics. As an example, in reference [1], Läuchli and Kollath numerically study quenches within the superfluid and Mott insulating phases of the 1D Bose-Hubbard

In other words, does the full, closed system serve as a good heat bath for itself, so that subsystems can be described by some statistical mechanical ensemble? References [3] and [4] are two examples from a vast literature that explores these questions theoretically and numerically. Meanwhile, thermalization following a quantum quench has also been explored experimentally using cold atoms, for instance by the Bloch group in reference